all: integrate changes made in cmd/go packages

This change integrates changes made to cmd/go packages into the
corresponding x/mod packages.

This is the second step of a bidirectional synchronization. The
previous step was CL 200138, which copied changes made in these
packages back into cmd/go. With this change, the cmd/go and x/mod
packages should be the same except for imports. After this change, we
can vendor x/mod into cmd, then remove the duplicate packages in

Other important changes:

* Updated requirement on to latest and added crypto is needed for ed25519, which was added
  to std in go1.13. xerrors is needed for unwrapping, which was also
  added in 1.13. The x versions of these are compatible with go1.12.
* Copied internal/lazyregexp from std, since it's used in sumdb.

Updates golang/go#34801

Change-Id: Iafdd0668970f9004e663040535c521241d11a6a8
Run-TryBot: Jay Conrod <>
TryBot-Result: Gobot Gobot <>
Reviewed-by: Bryan C. Mills <>
9 files changed